add CI job for checking wasm

Adds a CI job for ensuring the tokio-postgres crate builds on
the wasm32-unknown-unknown target without the default features.

.github/workflows/ci.yml

@@ -47,6 +47,33 @@ jobs:
           key: clippy-target-${{ runner.os }}-${{ steps.rust-version.outputs.version }}-${{ hashFiles('Cargo.lock') }}y
       - run: cargo clippy --all --all-targets
 
+  check-wasm32:
+    name: check-wasm32
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: sfackler/actions/rustup@master
+      - run: echo "version=$(rustc --version)" >> $GITHUB_OUTPUT
+        id: rust-version
+      - run: rustup target add wasm32-unknown-unknown
+      - uses: actions/cache@v3
+        with:
+          path: ~/.cargo/registry/index
+          key: index-${{ runner.os }}-${{ github.run_number }}
+          restore-keys: |
+            index-${{ runner.os }}-
+      - run: cargo generate-lockfile
+      - uses: actions/cache@v3
+        with:
+          path: ~/.cargo/registry/cache
+          key: registry-${{ runner.os }}-${{ steps.rust-version.outputs.version }}-${{ hashFiles('Cargo.lock') }}
+      - run: cargo fetch
+      - uses: actions/cache@v3
+        with:
+          path: target
+          key: clippy-target-${{ runner.os }}-${{ steps.rust-version.outputs.version }}-${{ hashFiles('Cargo.lock') }}y
+      - run: cargo check --target wasm32-unknown-unknown --manifest-path tokio-postgres/Cargo.toml --no-default-features
+
   test:
     name: test
     runs-on: ubuntu-latest